How do you determine which triaxial accelerometer meets my application needs?
Triaxial accelerometers measure acceleration in three perpendicular axis (X, Y, Z). There are two primary advantages of using a triaxial accelerometer over three single axis units. First, mounting (stud, screw, adhesive) is in one location rather than three. Second, cable installation and connection to instrumentation is typically easier and takes less time.
Use the Endevco product selection tool. to find the 3 axis accelerometer that best meets your application needs. This user-friendly interface allows you to query the accelerometer database by product specifications (i.e. output type, sensitivity, weight) and/or industry (i.e. automotive design/testing, transportation testing, general lab testing).
Meggitt designs and manufactures triaxial accelerometers using a wide range of technology platforms (Piezoresistive, Variable Capacitance, Piezoelectric, and Integrated Electronics Piezoelectric) to meet project requirements across many industries.
3 axis accelerometers generally have low sensitivity making them desirable for shock measurements. PR accelerometers have a wide bandwidth and the frequency response goes down to zero Hz (often called “DC responding”) or steady state, so they can measure long duration transients.
The Model 74 series is a family of rugged, lightly damped, piezoresistive triaxial accelerometers designed for high-acceleration shock measurements in three mutually perpendicular axes. This family uses three sensors that are packaged in a mutually orthogonal arrangement in a leadless chip carrier (LCC) package that supports mounting by surface mount technology (SMT) re-flow soldering (with epoxy under fill) or adhesive mounting (with hand soldering).
Model 74 is available in 20,000 g and 60,000 g full scale ranges, with all three axs having the same range.
Variable Capacitance (VC) Technology
Variable capacitance is among the newer accelerometer technologies. Like PR accelerometers, they are DC responding. VC accelerometers have high sensitivities, a narrow bandwidth and outstanding temperature stability. These devices are highly desirable for measuring low frequency vibration, motion and steady state acceleration.
The Model 7298 triax accelerometer family is designed to provide the high thermal stability and global accuracy that is typically required for the measurement of relatively low-level accelerations in aerospace and automobile environments. State of the art temperature compensation electronics provide precise compensation over a wide temperature range, while maintaining a full analog signal path. Each axis of the triaxial accelerometer utilizes a patented variable capacitance MEMS sensing element. Gas damping and internal over range stops enable the sensor to withstand high shock and acceleration loads.
Piezoelectric (PE) Technology
PE accelerometers are among the most widely used accelerometers for test and measurement applications. These devices offer a very wide measurement frequency range (a few Hz to 30 kHz) and are available in a wide range of sensitivities, weights, sizes and shapes. These accelerometers can be considered for both shock and vibration measurements.
The Model 2230E or 2230EM1 are miniature triaxial piezoelectric accelerometers designed specifically for vibration measurement on small structures and objects. This high temperature (+260ºC) transducer features three M3 receptacles for output connection. Its light weight (17 grams) effectively minimizes mass-loading effects. The accelerometer is a self-generating device that requires no external power source for operation. Low-noise, flexible coaxial cables are supplied for error-free operation.
Piezoelectric Accelerometer with Integrated Electronics (IEPE) Technology
Basically, an IEPE accelerometer is a PE device with the charge amplifier built-into the accelerometer. It requires no external charge amplifiers and uses ordinary low cost cable. The accelerometer does require a constant current power source and many data acquisition systems have built-in power sources. If the user knows the vibration range and the operating temperature is in the range of -55˚C (-67˚F) to 125˚C (257˚F) then an IEPE device should be considered. Note that high temperature versions are available in some models that have a maximum operating temperature of 175˚C (350˚F).
Model 35B is an ultra-miniature, adhesive mounted triaxial IEPE accelerometer with integral electronics. Its tiny size, 0.235 inch cube, and light weight, 0.55 grams (sensor only), make it ideal for measuring vibration on very small objects. The 35B has an integral three-foot cable that terminates to a single threaded ¼-28 4-pin connector. The accelerometer incorporates an internal hybrid signal conditioner in a two-wire system, which transmits its low impedance voltage output through the same cable that supplies the required constant current power. The case is isolated from the mounting surface by an anodized coating over the accelerometer’s aluminum housing.